PARIS — Attacking a sacred cow — or at least getting it to work more than 35 hours a week — is proving a difficult assignment for President Nicolas Sarkozy.

The reform-minded French president found himself in another political muddle as top members of his ruling party contradicted each other yesterday over one of the president’s prime goals: easing the 10-year-old law mandating a 35-hour workweek.

The mixed signals over a policy Mr. Sarkozy once called an “economic catastrophe” are seen by many here as symbolic of the president’s first year in office, which he marked earlier this month. Although the energetic Mr. Sarkozy was hailed as a sharp break with past French leaders, he has made only halting progress in overhauling French economic and social practices to make the country more competitive.

“He took over a country that was feeling insecure and which regarded him as the last chance to solve their structural problems,” wrote noted political analyst Dominique Moisi, but Mr. Sarkozy “failed to convince the French and offer them security.”

The 35-hour workweek, approved by the Socialist government in 1998 primarily as a way to create more jobs, is perhaps the ultimate symbol of the elaborate social safety net that Mr. Sarkozy vowed to change.

Top party leaders of his center-right Union for a Popular Movement (UMP) party now appear to be of two minds over how to confront the politically delicate program, strongly backed by the country’s powerful labor unions.

Speaking on the 10th anniversary of the law’s introduction, UMP party chief Patrick Devedjian demanded its “definitive dismantlement,” according to Reuters news agency.

Shortly afterward, the party’s second in command, former Prime Minister Jean-Pierre Raffarin, said the UMP had no intention of increasing the number of hours employees must work, but rather wanted to give companies incentive to offer overtime.

Mr. Sarkozy later weighed in on the side of caution, saying a frontal assault on the workweek law isn’t in the cards for now.

Many allies think Mr. Sarkozy should be bolder and force the issue. Mr. Devedjian argued that it was time to let each company establish its own working conditions directly with unions.

“The UMP is forcefully requesting the definitive dismantlement of the 35-hour week, and that the length of work be negotiated company by company,” he said.

“It is obvious we don’t want to touch the legal workweek,” he told LCI television, adding that Mr. Devedjian had meant that firms and unions should merely “discuss” overtime arrangements.

The Socialists voted in May 1998 to reduce the workweek from 39 to 35 hours with no loss of pay, despite the fact that none of France’s major competitors was doing likewise.

Even some senior leftists have questioned the wisdom of the change, but French workers have grown used to their extra leisure time and Mr. Sarkozy has split the difference by leaving the law on the books and offering tax breaks to encourage overtime.

Elected last year on the mantra “work more to earn more,” Mr. Sarkozy has used the overtime initiative as a reason not to tackle the bigger question of the shorter mandated workweek.

“It is not the government’s intention to abolish the legal working limit because it is the base point for calculating overtime,” he told lawmakers in January.

However, most firms have failed to boost overtime despite the incentives.

A survey showed the French were world champions when it came to holidays, enjoying an average of 37 days of paid vacation a year, compared with 27 in Germany, 26 in Britain and 14 in the United States.

A study last year by economists from the International Monetary Fund said the 35-hour workweek had had a “mainly negative impact” on French competitiveness, economic growth and job creation.

“It failed to create more jobs and generated a significant — mostly negative — reaction both from companies and workers as they tried to neutralize the law’s effect on hours of work and monthly wages,” IMF analysts Marcello Estevao and Filipa Sa concluded.

As prime minister in 2004 under President Jacques Chirac, Mr. Raffarin helped push through an amendment increasing the number of overtime hours employees can work in a year from 180 to 220. The parliament in 2005 also broadened the ways employers can offer overtime pay.

But any move to sink the 35-hour week entirely is certain to meet fierce resistance from French unions, who are already upset over a government pension reform and moves to cut France’s army of public-sector workers.